Information management systems are being developed to track the location and/or status of a large variety of mobile entities such as products, vehicles, people, animals, etc. A widely used tracking technology uses so-called RFID tags that are placed physically on the items being tracked. Reference herein to “items” being tracked is intended to include the variety of entities just mentioned as well as, more commonly, product inventories.
RFID tags may be active or passive. Active tags typically have associated power systems and can transmit data over modest distances. Passive systems lack internal power but derive transmitting signal power from an incoming RF signal. However, transmitting distances with passive RFID tags are limited. To read a large number of RFID tags, spread over a wide physical area, requires either a large number of RFID readers, or a reliable system of moving RFID readers. One proposed solution to this problem is to use active RFID tags on the products. However, active tags are relatively costly. Although they lend more function to a tracking system, and transmit more effectively, passive tags are typically more cost effective where inventories being tracked are large.
In practical commercial applications, passive RFID devices should be inexpensive and easily applied to items being tracked. A common approach is to form the RF components on a small RF IC device. The RF IC device and the RF antenna are mounted on a substrate, typically paper or plastic.
In the manufacture of inexpensive RFID tags, like that just described, fabricating the combination of the RF IC chip and the RF antenna on a suitable inexpensive substrate, and attaching the substrate to the item being tracked to the substrate poses technical and economic challenges.
An attractive solution to these challenges is described and claimed in U.S. Patent Publication 20080061983. The RF antenna is formed as a serpentine metal runner on a substrate. The RFIC device is bonded to a ceramic chip carrier and the ceramic chip carrier is capacitively connected to the antenna. This solution is effective but adds another element, and additional cost, to the RFID tag.